The Storage test workloads are repeated. Between each repetition, the storage system is bombarded with a usage that causes degraded drive performance. In the first part of the test, the cycle continues until a steady degraded level of performance has been reached. (Steady State)

In the second part, the recovery of the system is tested by allowing the system to idle and measuring the performance after 5-minute long intervals. (Internal drive maintenance: Garbage Collection (GC)) The test reports the performance level at the start, the degraded steady-state, and the recovered state, as well as the number of iterations required to reach the degraded state and the recovered state.

We feel Futuremark's Consistency Test is the best test ever devised to show the true performance of solid state storage in an extended duration heavy workload environment. This test takes on average 13 to 17 hours to complete and writes somewhere between 450GB and 14,000GB of test data depending on the drive. If you want to know what an SSDs steady state performance is going to look like during a heavy workload, this test will show you.

Here's a breakdown of Futuremark's Consistency Test:

Precondition phase:

1. Write to the drive sequentially through up to the reported capacity with random data.

2. Write the drive through a second time (to take care of overprovisioning).

Degradation phase:

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for 10 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 8 times, and on each pass increase the duration of random writes by 5 minutes.

Steady state phase:

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for 50 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 5 times.

Recovery phase:

1. Idle for 5 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 5 times.

Storage Bandwidth

PCMark 8's Consistency test provides a ton of data output that we use to judge a drive's performance.

We consider steady state bandwidth (the blue bar) our test that carries the most weight in ranking a drive/arrays heavy workload performance. Performance after Garbage Collection (GC) (the orange and red bars) is what we consider the second most important consideration when ranking a drive's performance. Trace-based steady state testing is where true high performing SSDs are separated from the rest of the pack.

Focusing in on steady-state performance again reveals why we believe the 4TB EVO is the fastest SATA SSD ever made. This result again goes back to why we believe that the often used line that the SATA III interface has long been maxed out is an incorrect statement. In a steady-state environment, the 4TB EVO has no competition.

Samsung has found a way to improve the steady-state performance of the 4TB EVO over that of the 2TB EVO by a whopping 51%. A steady-state performance of 221.07 MB/s is a new lab record for a SATA SSD.

We chart our test subject's storage bandwidth as reported at each of the test's 18 trace iterations. This gives us a good visual perspective of how our test subjects perform as testing progresses. This chart sheds more light on how the drives perform as they progress through the testing phases.

Total Access Time (Latency)

We chart the total time the disk is accessed as reported at each of the test's 18 trace iterations.

Low latency translates to the real-world as snappiness.

Disk Busy Time

Disk Busy Time is how long the disk is busy working. We chart the total time the disk is working as reported at each of the tests 18 trace iterations.

When latency is low, disk busy time is low as well.

Data Written

We measure the total amount of random data that our test drive/array is capable of writing during the degradation phases of the consistency test. Pre-conditioning data is not included in the total. The total combined time that degradation data is written to the drive/array is 470 minutes. This can be very telling. The better a drive/array can process a continuous stream of random data; the more data will be written.

Overprovisioning and write latency are the biggest factors that determine the outcome of this portion of the test. The 4TB EVO places third in this test. OWC's 2TB Mercury Electra manages to win this test due to its massive 260GB of overprovisioning.

PRICING: You can find the Samsung 850 EVO 4TB SATA III SSD for sale below. The prices listed are valid at the time of writing, but can change at any time. Click the link below to see real-time pricing for the best deal:

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